In space vehicles, liquid propellant tends to shift and slosh in storage tanks under acceleration during launch and responsive to tank movement in low-gravity environments (e.g., in space, in orbit around the Earth), potentially causing shifting of a center of mass of a space vehicle incorporating such storage tanks, resulting in undesirable vibrations, and vehicle control problems. In an attempt to reduce the sloshing, some conventional liquid storage tanks include structures therein to provide obstacles to the sloshing. Furthermore, in low-gravity environments the liquid may be positioned in any location within the storage tanks, and not necessarily at an outlet of the storage tanks. Thus, the structures may also be configured to provide surfaces that may be “wetted” by the liquid within the storage tanks, to direct the liquid toward an outlet via surface tension.
In addition, it is difficult to determine an amount of liquid in a tank in a low-gravity environment (e.g., in space, in orbit around the Earth), since the liquid does not tend to settle to a predictable side or end of the storage tank absent significant, directed gravitational or acceleration forces.